Light emitting device, backlight, and display panel

ABSTRACT

The present disclosure provides a light emitting device including a substrate, a conductive layer, first and second reflective layers, a light emitting element, and an encapsulation layer. The conductive layer is disposed on the substrate. The first reflective layer covers the conductive layer and has an opening exposing a portion of the conductive layer. The light emitting element is disposed in the opening and electrically connects to the conductive layer. The second reflective layer is disposed on the first reflective layer and surrounds the light emitting element, and the second reflective layer has an outer diameter. The encapsulation layer covers the light emitting element. There is a height between a highest point of the encapsulation layer and an upper surface of the first reflective layer, and the height is 0.1 to 0.5 times the outer diameter. The present disclosure also provides a backlight and a display panel.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to China Application Serial Number202011306944.3, filed Nov. 20, 2020, which is herein incorporated byreference.

BACKGROUND Field of Invention

The present disclosure relates to a light emitting device, a backlight,and a display panel.

Description of Related Art

With the advancement of light emitting diode technologies and increasingmarket demand, novel display technologies represented by mini-lightemitting diodes/micro-light emitting diodes (Mini-LEDs/Micro-LEDs) haveemerged.

The Mini-LED packaging mainly includes chip on board (COB) technologyand integrated mounted device (IMD) packaging technology. The COBtechnology is to directly mount the LED chip on the module substrate,and then mold each large unit as a whole. However, various existing COBpackaging technology still have many problems such as high productioncosts, serious light loss, and poor product stabilities.

SUMMARY

In view of this, one goal of the present disclosure is to provide alight emitting device, a backlight, and a display panel capable ofaddressing the aforementioned issues.

One aspect of the present disclosure is to provide a light emittingdevice including a substrate, a conductive layer, a first reflectivelayer, a light emitting element, a second reflective layer, and anencapsulation layer. The conductive layer is disposed on the substrate.The first reflective layer covers the conductive layer and has anopening exposing a portion of the conductive layer. The light emittingelement is disposed in the opening and electrically connects to theconductive layer. The second reflective layer is disposed on the firstreflective layer and surrounds the light emitting element, and thesecond reflective layer has an outer diameter. The encapsulation layercovers the light emitting element. There is a height between a highestpoint of the encapsulation layer and an upper surface of the firstreflective layer, and the height is 0.1 to 0.5 times the outer diameter.The present disclosure also provides a backlight and a display panel.

According to one embodiment of the present disclosure, the secondreflective layer has an inner diameter, and a difference between theouter diameter and the inner diameter ranges from 0.05 mm to 0.6 mm.

According to one embodiment of the present disclosure, the firstreflective layer and the second reflective layer respectively include awhite ink.

According to one embodiment of the present disclosure, a top surface ofthe second reflective layer is lower than a top surface of the lightemitting element.

According to one embodiment of the present disclosure, the secondreflective layer has a thickness, and the thickness ranges from 20 um to60 um.

According to one embodiment of the present disclosure, the outerdiameter ranges from 2.0 mm to 4.5 mm.

According to one embodiment of the present disclosure, the encapsulatinglayer fully covers the second reflective layer.

According to one embodiment of the present disclosure, the encapsulatinglayer has an arc-shaped outer surface.

According to one embodiment of the present disclosure, the encapsulatinglayer has a width gradually decreasing by a constant amount from bottomto top, and the encapsulating layer has an arc-shaped top surface.

According to one embodiment of the present disclosure, the encapsulatinglayer has a width gradually decreasing by a constant amount from bottomto top, and the encapsulating layer has a flat top surface.

Another aspect of the present disclosure is to provide a backlightincluding a plurality of light emitting devices foregoing. Any twoadjacent light emitting devices are separated by a distance, and theouter diameter is less than 0.5 times the distance.

Yet another aspect of the present disclosure is to provide a displaypanel including a backlight foregoing, a lower diffuser, a quantum dotlayer, an optical film, an upper diffuser, and a liquid crystal panel.The lower diffuser is disposed on the backlight. The quantum dot layeris disposed on the lower diffuser. The optical film is disposed on thequantum dot layer. The upper diffuser is disposed on the optical film.The liquid crystal panel is disposed over the upper diffuser.

According to one embodiment of the present disclosure, the optical filmincludes a prism sheet.

According to one embodiment of the present disclosure, the optical filmincludes a brightness enhancement film.

According to one embodiment of the present disclosure, the quantum dotlayer includes a red quantum dot, a green quantum dot, a blue quantumdot, or combinations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure can be more fully understood by reading the followingdetailed description of the embodiment, with reference made to theaccompanying drawings as follows.

FIG. 1A illustrates a three-dimensional schematic view of a lightemitting device according to one comparative example of the presentdisclosure.

FIG. 1B illustrates a cross-section schematic view of the light emittingdevice of FIG. 1A.

FIG. 2 illustrates a cross-section schematic view of a light emittingdevice according to another comparative example of the presentdisclosure.

FIG. 3 illustrates a cross-section schematic view of manufacturing alight emitting device according to yet another comparative example ofthe present disclosure.

FIG. 4 illustrates a cross-section schematic view of a light emittingdevice according to one embodiment of the present disclosure.

FIGS. 5A, 5B, and 5C illustrate a schematic top view of a secondreflective layer according to various embodiments of the presentdisclosure.

FIG. 6 illustrates a cross-section schematic view of a light emittingdevice according to one embodiment of the present disclosure.

FIG. 7A is a diagram showing a path of light emitted by a light emittingdevice according to one embodiment of the present disclosure.

FIG. 7B is a schematic diagram showing the uniformity of light emittedby a light emitting device according to one embodiment of the presentdisclosure.

FIG. 7C is a diagram showing a path of light emitted by a light emittingdevice according to another embodiment of the present disclosure.

FIG. 7D is a schematic diagram showing the uniformity of light emittedby a light emitting device according to another embodiment of thepresent disclosure.

FIGS. 8A, 8B, 8C, and 8D illustrate cross-section schematic views of alight emitting device according to various embodiments of the presentdisclosure.

FIGS. 9A and 9B are schematic diagrams showing the light emissionuniformity before and after processing the encapsulating layer of alight emitting device according to one embodiment of the presentdisclosure.

FIG. 10 illustrates a cross-section schematic view of a backlightaccording to one embodiment of the present disclosure.

FIG. 11 illustrates a cross-section schematic view of a display panelaccording to one embodiment of the present disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. The embodiments disclosedbelow may be combined or substituted with each other under beneficialcircumstances, and other embodiments may also be added to an embodimentwithout further description.

It will be understood that, although the terms “first,” “second,”“third” etc. may be used herein to describe various elements,components, regions, layers and/or sections, these elements, components,regions, layers and/or sections should not be limited by these terms.These terms are only used to distinguish one element, component, region,layer or section from another element, component, region, layer orsection. Thus, a first element, component, region, layer or sectiondiscussed below could be termed a second element, component, region,layer or section without departing from the teachings of the presentinvention.

In the following description, certain specific details are set forth inorder to provide a thorough understanding of various embodiments of thedisclosure. However, one skilled in the art will understand that thedisclosure may be practiced without these specific details. Furthermore,for simplifying the drawings, some of the conventional structures andelements are shown with schematic illustrations.

FIG. 1A illustrates a three-dimensional schematic view of a lightemitting device 10 according to one comparative example of the presentdisclosure. FIG. 1B illustrates a cross-section schematic view of thelight emitting device 10 of FIG. 1A. Referring to FIGS. 1A and 1B, thelight emitting device 10 includes a printed circuit board 110, aplurality of light emitting diodes 120, and an encapsulating glue 130.The light emitting diodes 120 are arranged on the printed circuit board110 at intervals. The encapsulating glue 130 fully covers the printedcircuit board 110 and the light emitting diodes 120. It is noted thatthe encapsulating glue 130 fully covers the printed circuit board 110and the light emitting diodes 120 by fully coating method. As a result,the surface flatness of the light emitting device 10 is greatly reduced,and the product specifications cannot be met. Furthermore, this methodof fully coating the encapsulating glue 130 will also cover thenon-light emitting area of the light emitting device 10 at the sametime, and will increase the cost, thereby causing the reduction of theproduct competitiveness.

FIG. 2 illustrates a cross-section schematic view of a light emittingdevice 20 according to another comparative example of the presentdisclosure. Referring to FIG. 2, the light emitting device 20 includes aprinted circuit board 210, a light emitting diode 220, a ring-shaped dam230, and an encapsulating glue 240. It can be understood that theprinted circuit board 210 includes a substrate 212, a conductive layer214 disposed on the substrate 212, and a solder protection layer 216disposed on the conductive layer 214. The light emitting diode 220 isdisposed on the conductive layer 214 of the printed circuit board 210 toelectrically connect to the conductive layer 214. The ring-shaped dam230 is disposed on the solder protection layer 216 of the printedcircuit board 210 and surrounds the light emitting diode 220. Generallyspeaking, the ring-shaped dam 230 may be made of insulating material,and the insulating material is, for example, silicon. The encapsulatingglue 240 is filled in the ring-shaped dam 230 and covers the lightemitting diode 220. Due to the higher viscosity material of thering-shaped dam 230, the width and height of the ring-shaped dam 230formed therefrom are both larger than the width and height of the lightemitting diode 220. Therefore, the light emitting device 20 is likely tocause light loss and not suitable for forming a large-size light board.

FIG. 3 illustrates a cross-section schematic view of manufacturing alight emitting device 30 according to yet another comparative example ofthe present disclosure. The light emitting device 30 includes a printedcircuit board 310, a light emitting diode 320, and a transparent cover330. The light emitting diode 320 is disposed on the printed circuitboard 310. The transparent cover 330 seals the single light emittingdiode 320 disposed on the printed circuit board 310. To be specific, thetransparent cover 330 is formed by compression molding method. Thematerials of the transparent cover 330 include silicon resin, epoxyresin, and glass. However, the production and the operation of thecompression molding equipment are very expensive, and the stability ofthe large-size molding products is also poor.

FIG. 4 illustrates a cross-section schematic view of a light emittingdevice 40 according to one embodiment of the present disclosure.Referring to FIG. 4, the light emitting device 40 includes a substrate410, a conductive layer 420, a first reflective layer 430, a lightemitting element 440, a second reflective layer 450, and anencapsulating layer 460. In some embodiments, the substrate 410 may bean insulating substrate, an aluminum composite substrate, a flexiblesubstrate, or a ceramic substrate. The conductive layer 420 is disposedon the substrate 410. In some embodiments, the conductive layer 420 mayinclude conductive materials of copper, aluminum, nickel, silver, gold,palladium, or combinations thereof. The first reflective layer 430covers the conductive layer 420, and the first reflective layer 430 hasan opening 432 exposing a portion of the conductive layer 420. In someembodiments, the material of the first reflective layer 430 is a whiteink. Specifically, the material of the white ink is a white text inkcontaining highly reflective titanium dioxide. This material not onlyhas a highly reflectivity, but also has the effects of high heatresistance (for example, yellowing resistance and stress crackingresistance) and high reliability.

Referring to FIG. 4, the light emitting element 440 is disposed in theopening 432 and electrically connected to the conductive layer 420. Insome embodiments, the light emitting element 440 may be a mini-LED or amicro-LED. For example, the light emitting element 440 may be a redmini-LED, a red micro-LED, a green mini-LED, a green micro-LED, a bluemini-LED, a blue micro-LED, a yellow mini-LED, a yellow micro-LED, awhite mini-LED, or a white micro-LED. In some embodiments, the lightemitting element 440 is flip-chip bonded to and in contact with theconductive layer 420.

Referring to FIG. 4, the second reflective layer 450 is disposed on thefirst reflective layer 430 and surrounds the light emitting element 440.More specifically, the second reflective layer 450 has an outer diameterDout. In some embodiments, the outer diameter Dout ranges from 2.0 mm to4.5 mm. For example, the outer diameter Dout may be 2.1 mm, 2.3 mm, 2.5mm, 2.7 mm, 2.9 mm, 3.0 mm, 3.1 mm, 3.3 mm, 3.5 mm, 3.7 mm, 3.9 mm, 4.0mm, 4.1 mm, or 4.3 mm. In some embodiments, the second reflective layer450 has an inner diameter Din, and a difference between the outerdiameter Dout and the inner diameter Din ranges from 0.05 mm to 0.6 mm,such as 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45mm, 0.5 mm, or 0.55 mm. If the difference between the outer diameterDout and the inner diameter Din is less than a certain value, such as0.05 mm, the subsequent process of forming the encapsulating layer willcause insufficient cohesion of encapsulating glue, thereby causing theglue to overflow and the height of the encapsulating layer not easy toimprove. On the other hand, if the difference between the outer diameterDout and the inner diameter Din is greater than a certain a value, suchas 0.6 mm, the amount of the encapsulating glue used will increase, andthe process time for forming the encapsulating layer will also beprolonged.

In some embodiments, the material of the second reflective layer 450 isa white ink. Specifically, the material of the white ink is a white textink containing highly reflective titanium dioxide. This material notonly has a highly reflectivity, but also has the effects of high heatresistance (for example, yellowing resistance and stress crackingresistance) and high reliability. In some embodiments, a top surface ofthe second reflective layer 450 is lower than a top surface of the lightemitting element 440. In some embodiments, a thickness TH of the secondreflective layer 450 ranges from 20 um to 60 um, such as 25 um, 30 um,35 um, 40 um, 45 um, 50 um, or 55 um. If the thickness TH of the secondreflective layer 450 is less than a certain value, such as 20 um, thesubsequent process of forming the encapsulating layer will causeinsufficient cohesion of encapsulating glue, thereby causing the glue tooverflow and the height of the encapsulating layer not easy to improve.On the other hand, if the thickness TH of the second reflective layer450 is greater than a certain a value, such as 60 um, the secondreflective layer 450 will be not easy to form and easy to collapse. Insome embodiments, the second reflective layer 450 may be formed byprinting or coating, so that the expected position, the width, and thethickness of the second reflective layer 450 can be controlled moreaccurately.

FIGS. 5A, 5B, and 5C illustrate a schematic top view of the secondreflective layer 450 according to various embodiments of the presentdisclosure. As shown in FIG. 5A, the shape of the second reflectivelayer 450 viewed in the top view direction may be a circle, in oneembodiment. As shown in FIG. 5B, the shape of the second reflectivelayer 450 viewed in the top view direction may be a triangle havingfillets, in another embodiment. As shown in FIG. 5C, the shape of thesecond reflective layer 450 viewed in the top view direction may be asquare having fillets, in yet another embodiment. In other alternativeembodiments, the shape of the second reflective layer 450 viewed in thetop view direction may be a polygon having fillets. It is noted thatregardless of the shape of the second reflective layer 450 observed inthe top view direction, it has a virtual geometric circumscribed circle(as shown by the dashed line in FIGS. 5A-5C) and a virtual geometricinscribed circle (as shown by the dashed line in FIGS. 5A-5C). Thegeometric circumscribed circle has an outer diameter Dout and thegeometric inscribed circle has an inner diameter Din, and a differencebetween the outer diameter Dout and the inner diameter Din ranges from0.05 mm to 0.6 mm.

Referring to FIG. 4 again, the encapsulating layer 460 covers the lightemitting element 440. More specifically, there is a height H between ahighest point of the encapsulating layer 460 and an upper surface of thefirst reflective layer 430, and the height H is 0.1 to 0.5 times theouter diameter Dout. For example, the height H may be 0.2, 0.3, or 0.4times the outer diameter Dout. In some embodiments, the encapsulatinglayer 460 covers the light emitting element 440 and a portion of thefirst reflective layer 430, but not covers the second reflective layer450. In other words, the encapsulating layer 460 is merely disposedwithin an inner edge of the second reflective layer 450. To put itanother way, the range covered by the encapsulating layer 460 onlycovers the inner diameter Din of the second reflective layer 450. Insome embodiments, the encapsulating layer 460 has an arc-shaped outersurface. In some embodiments, the encapsulating layer 460 may be formedby dispensing or jetting. In some embodiments, the encapsulating layer460 may include an organic packaging material, an inorganic packagingmaterial, or combinations thereof. For example, the organic packagingmaterial includes silicon rubber, acrylic and epoxy resin, while theinorganic packaging material includes silicon dioxide and fluorineadhesive. However, the present disclosure is not limited thereto. Theencapsulating layer 460 can increase the area capable to block moistureand protect the light emitting element 440 from moisture, therebyincreasing the reliability and service life of the product. In addition,the encapsulating layer 460 may also act as a lens to change the lightemitting angle of the light emitting element 440.

FIG. 6 illustrates a cross-section schematic view of a light emittingdevice 60 according to one embodiment of the present disclosure. Inorder to facilitate the comparison with the aforementioned embodimentsand simplify the description, the same reference numbers are used in thefollowing embodiments to refer to the same or like parts. Also, thedifferences between embodiments are discussed below, and similar partswill not be repeated. The difference between the light emitting device60 and the light emitting device 40 is that the encapsulating layer 460of the light emitting device 60 completely covers the second reflectivelayer 450. Compared with the light emitting device 40, the lightemitting device 60 has more uniform light emission and can improve thevisual effect of applications thereof.

FIG. 7A is a diagram showing a path of light emitted by the lightemitting device 60 according to one embodiment of the presentdisclosure. FIG. 7B is a schematic diagram showing the uniformity oflight emitted by the light emitting device 60 according to oneembodiment of the present disclosure. FIG. 7C is a diagram showing apath of light emitted by the light emitting device 60 according toanother embodiment of the present disclosure. FIG. 7D is a schematicdiagram showing the uniformity of light emitted by the light emittingdevice 60 according to another embodiment of the present disclosure. Itis noted that FIGS. 7A and 7B show the light emission path anduniformity of the light emitting device 60 under the design where theheight H between the highest point of the encapsulating layer 460 andthe upper surface of the first reflective layer 430 is 0.1 times theouter diameter Dout. FIGS. 7C and 7D show the light emission path anduniformity of the light emitting device 60 under the design where theheight H between the highest point of the encapsulating layer 460 andthe upper surface of the first reflective layer 430 is 0.5 times theouter diameter Dout. In various embodiments where the height H is 0.1times to 0.5 times the outer diameter Dout, it can be understood thatwhen the height H is closer to 0.5 times the outer diameter Dout, thelight emission uniformity of the light emitting device 60 is better.

FIGS. 8A and 8B illustrate cross-section schematic views of a lightemitting device 80 a and 80 b according to various embodiments of thepresent disclosure. As shown in FIGS. 8A and 8B, the encapsulating layer460 of the light emitting device 80 a and 80 b has a width graduallydecreasing by a constant amount from bottom to top and has an arc-shapedtop surface. From the schematic cross-sectional view, the slope of thesidewalls of the light emitting device 80 a and 80 b is a certain value.The difference between the light emitting device 80 a and the lightemitting device 80 b is that a radius of curvature of the arc-shaped topsurface of the encapsulating layer 460 of the light emitting device 80 ais smaller than that of the encapsulating layer 460 of the lightemitting device 80 b. Compared with the light emitting device 80 a, thearc-shaped top surface of the encapsulating layer 460 of the lightemitting device 80 b is a relatively smooth arc-shaped top surface. Insome embodiments, the sidewalls of the encapsulating layer 460 of thelight emitting device 80 a and 80 b may be flattened by post-processing.

FIGS. 8C and 8D illustrate cross-section schematic views of a lightemitting device 80 c and 80 d according to various embodiments of thepresent disclosure. As shown in FIGS. 8C and 8D, the encapsulating layer460 of the light emitting device 80 c and 80 d has a width graduallydecreasing by a constant amount from bottom to top, and theencapsulating layer has a flat top surface. From the schematiccross-sectional view, the slope of the sidewalls of the encapsulatinglayer 460 of the light emitting device 80 c and 80 d is a certain value.The difference between the light emitting device 80 c and the lightemitting device 80 d is that the area of the flat top surface of theencapsulating layer 460 of the light emitting device 80 c is smallerthan that of encapsulating layer 460 of the light emitting device 80 d.In some embodiments, the arc-shaped top surfaces of the light emittingdevice 80 a and 80 b may be processed into flat top surfaces by apost-processing planarization process, such as grinding or flatpolishing.

FIGS. 9A and 9B are schematic diagrams showing the light emissionuniformity before and after processing the encapsulating layer of alight emitting device according to one embodiment of the presentdisclosure. FIG. 9A is a schematic diagram of the light emissionuniformity of the encapsulating layer of the light emitting devicewithout post-processing. FIG. 9B is a schematic diagram of the lightemission uniformity of the encapsulating layer of the light emittingdevice after post-processing. It can be seen from FIGS. 9A and 9B thatthe light emitting device after post-processing has better lightemission uniformity than the light emitting device withoutpost-processing.

FIG. 10 illustrates a cross-section schematic view of a backlight 90according to one embodiment of the present disclosure. As shown in FIG.10, the backlight 90 includes a plurality of light emitting devices (40,60, 80 a, 80 b, 80 c, 80 d, or combinations thereof) foregoing. It isnoted that any two adjacent light emitting devices are separated by adistance P, and the outer diameter Dout is less than 0.5 times thedistance P. This design may reduce the amount encapsulating glue of thebacklight 90 overall. For example, the amount encapsulating glue may bereduced by more than 80%, thereby reducing costs and enhancing themarket competitiveness of products.

FIG. 11 illustrates a cross-section schematic view of a display panel1000 according to one embodiment of the present disclosure. As shown inFIG. 11, the display panel 1000 includes the backlight 90 foregoing, alower diffuser 1010, a quantum dot layer 1020, an optical film 1030, anupper diffuser 1040, and a liquid crystal panel 1050. To be specific,the lower diffuser 1010 is disposed on the backlight 90. The lowerdiffuser 1010 is used to increase a brilliancy of the display panel1000.

Referring to FIG. 11, the quantum dot layer 1020 is disposed on thelower diffuser 1010. In some embodiments, the quantum dot layer 1020includes a red quantum dot, a green quantum dot, a blue quantum dot, orcombinations thereof. The quantum dot layer 1020 can make the displaypanel 1000 have higher color purity and stronger color expression.

Referring to FIG. 11, the optical film 1030 is disposed on the quantumdot layer 1020. In some embodiments, the optical film 1030 includes aprism sheet or a brightness enhancement film (BEF). It can be understoodthat the number of the optical film 1030 is not limited to one as shownin FIG. 11, and the number of the optical film 1030 may be two or moredepending on design requirements. The main function of the optical film1030 is to achieve light collection, enhancement of the front lightemission, and increase of the brightness through the refraction andreflection of light. When the light diffuses out through the lowerdiffuser, the travelling direction of the light is not concentrated andthe directivity of the light is poor. Using the optical film 1030 tocorrect the travelling direction of the light may greatly increase theoverall brightness of the display panel 1000.

Referring to FIG. 11, the upper diffuser 1040 is disposed on the opticalfilm 1030. The upper diffuser 1040 may improve the light distribution toexpand the field of view. The upper diffuser 1040 may also make thelight emitted by the subsequent liquid crystal panel more uniform, sothat the display panel 1000 may have a soft and uniform surface lightsource.

Referring to FIG. 11, the liquid crystal panel 1050 is disposed over theupper diffuser 1040. In other embodiments, the display panel 1000 mayfurther include other optical components commonly used in this field tobetter enhance the visual performance of the display panel 1000.

In summary, the second reflective layer of the light emitting device ofthe present disclosure can control and divide accurately each lightemitting element. By effectively adjusting the height of theencapsulating layer to control the amount of glue materials to achievethe purpose of reducing production costs and improving product marketcompetitiveness. In addition, precisely controlling the relativerelationship between the outer diameter of the second reflective layerand the height of the encapsulating layer can further improve the visualeffects of the light emitting device and applications thereof (forexample, backlights and display panels).

Although the present disclosure has been described in considerabledetail with reference to certain embodiments thereof, other embodimentsare possible. It will be apparent to those skilled in the art thatvarious modifications and variations can be made to the structure of thepresent disclosure without departing from the scope or spirit of thedisclosure. In view of the foregoing, it is intended that the presentdisclosure cover modifications and variations of this disclosureprovided they fall within the scope of the following claims.

What is claimed is:
 1. A light emitting device, comprising: a substrate; a conductive layer disposed on the substrate; a first reflective layer covering the conductive layer, the first reflective layer having an opening exposing a portion of the conductive layer; a light emitting element disposed in the opening and electrically connected to the conductive layer; a second reflective layer disposed on the first reflective layer and surrounding the light emitting element, the second reflective layer having an outer diameter; and an encapsulating layer covering the light emitting element, a height between a highest point of the encapsulation layer and an upper surface of the first reflective layer being 0.1 to 0.5 times the outer diameter.
 2. The light emitting device of claim 1, wherein the second reflective layer has an inner diameter, and a difference between the outer diameter and the inner diameter ranges from 0.05 mm to 0.6 mm.
 3. The light emitting device of claim 1, wherein the first reflective layer and the second reflective layer respectively comprise a white ink.
 4. The light emitting device of claim 1, wherein a top surface of the second reflective layer is lower than a top surface of the light emitting element.
 5. The light emitting device of claim 1, wherein the second reflective layer has a thickness, and the thickness ranges from 20 um to 60 um.
 6. The light emitting device of claim 1, wherein the outer diameter ranges from 2.0 mm to 4.5 mm.
 7. The light emitting device of claim 1, wherein the encapsulating layer fully covers the second reflective layer.
 8. The light emitting device of claim 1, wherein the encapsulating layer has an arc-shaped outer surface.
 9. The light emitting device of claim 1, wherein the encapsulating layer has a width gradually decreasing by a constant amount from bottom to top, and the encapsulating layer has an arc-shaped top surface.
 10. The light emitting device of claim 1, wherein the encapsulating layer has a width gradually decreasing by a constant amount from bottom to top, and the encapsulating layer has a flat top surface.
 11. A backlight, comprising: a plurality of light emitting devices of claim 1, wherein any two adjacent light emitting devices are separated by a distance, and the outer diameter is less than 0.5 times the distance.
 12. A display panel, comprising: the backlight of claim 11; a lower diffuser disposed on the backlight; a quantum dot layer disposed on the lower diffuser; an optical film disposed on the quantum dot layer; an upper diffuser disposed on the optical film; and a liquid crystal panel disposed over the upper diffuser.
 13. The display panel of claim 12, wherein the optical film comprises a prism sheet.
 14. The display panel of claim 12, wherein the optical film comprises a brightness enhancement film.
 15. The display panel of claim 12, wherein the quantum dot layer comprises a red quantum dot, a green quantum dot, a blue quantum dot, or combinations thereof. 